ENVIRONMENTAL IMPACT ASSESSMENT ADDENDUM
for the SOUTH LUZON TOLLWAYS EXTENSION PROJECT
for South Luzon Tollways Corporation
TABLE OF CONTENTS
TABLE OF CONTENTS
2
PROJECT DESCRIPTION.............................................................................................. 1
2.1
INTRODUCTION.......................................................................................................... 1
2.2
PROJECT LOCATION .................................................................................................. 1
2.3
BRIEF DESCRIPTION OF THE PROJECT ...................................................................... 1
2.3.1
Project Specifications .......................................................................................... 1
2.3.1.1
2.3.1.2
2.3.1.3
2.3.2
2.3.3
Alabang Viaduct Rehabilitation (TR-1) ..................................................................... 5
Alabang to Calamba (TR-2)...................................................................................... 5
Calamba, Laguna to Santo Tomas, Batangas (TR-3) .............................................. 6
Summary of Major Structures.............................................................................. 6
Design Criteria and Standards ............................................................................ 7
2.3.3.1
2.3.3.2
Geometric Standards................................................................................................ 7
Engineering Design Standards................................................................................. 9
LIST OF TABLES
TABLE 2. 1
TABLE 2. 2
TABLE 2. 3
TABLE 2. 4
TABLE 2. 5
SUMMARY OF STRUCTURAL WORKS........................................................................................ 6
STANDARDS AND TECHNICAL SPECIFICATIONS-TOLL ROAD 2................................................... 7
STANDARDS AND TECHNICAL SPECIFICATIONS – TOLL ROAD 3 ................................................ 8
STANDARDS AND TECHNICAL SPECIFICATIONS – NEW RAMPS ................................................. 9
ENGINEERING DESIGN STANDARDS ...................................................................................... 10
LIST OF FIGURES
FIGURE 2. 1 LOCATION MAP OF THE PROJECT AREA................................................................................... 2
FIGURE 2. 2 VICINITY MAP OF THE STUDY AREA ......................................................................................... 3
FIGURE 2. 3 SCHEMATICS OF THE PROJECT ............................................................................................... 4
TEST CONSULTANTS, INC.
PROJECT DESCRIPTION - 1
2
PROJECT DESCRIPTION
2.1
INTRODUCTION
The CALABARZON is one of the more progressive and rapidly industrializing areas
in Southern Luzon. CALABARZON consists of the provinces of Batangas, Cavite,
Laguna, Quezon and Rizal. It is bounded by Metro Manila, Camarines Norte,
Camarines Sur, Pacific Ocean, South China Sea and Sulu Sea.
As an industrial growth center, it has been attracting a lot of investments, both
domestic and foreign. One aspect that makes it a favorable climate for investment is
its proximity Metro Manila and to major transport networks and facilities.
The South Luzon Expressway and the Southern Tagalog Arterial Road are two major
arteries to the CALABARZON Area.
2.2
PROJECT LOCATION
The Study area covers the alignment from the Alabang Viaduct located at Muntinlupa
City, Metro Manila to Calamba, Laguna ending at the STAR Ramp at Sto. Tomas,
Batangas. Figure 2.1 shows the location of the study area.
Figure 2.2 Vicinity Map shows the major landmarks such as the project sites, political
boundaries and the delineation of primary and secondary impact areas.
2.3
BRIEF DESCRIPTION OF THE PROJECT
2.3.1
Project Specifications
The project is to rehabilitate, expand, operate and maintain, under a 30-year
concession, the South Luzon Expressway linking the Alabang suburb south of Metro
Manila with the southern provinces of Laguna and Batangas. Figure 2.3 presents
the schematics of the project. The project comprises three (3) components namely:
1. Full rehabilitation and upgrading of the existing six-lane Alabang viaduct.
This would entail the construction of a new eight-lane superstructure and
retrofitting of the existing substructures – Toll Road 1 (TR-1).
2. Full rehabilitation, upgrading and expansion of the existing toll road from
Alabang, Muntinlupa City to Santa Rosa from four (4) lanes to eight (8) lanes
and from Santa Rosa to Calamba from four (4) lanes to six (6) lanes – Toll
Road 2 (TR-2). The total length of this section is 27.3 Kilometers.
3. Construction of a four (4)-lane toll road 7.6-km extension from Calamba in
Laguna Province to Santo Tomas in Batangas province (TR-3), linking the
South Luzon Expressway (SLEX) with the Southern Tagalog Arterial Road
(STAR). This is a new road that would be the vital connection of SLEX with
the STAR Tollway.
2.3.1.1
Alabang Viaduct Rehabilitation (TR-1)
The rehabilitation works in this section will consist of a post-tensioned segmental box
girder superstructure with spans of 30, 35 and 40 meters for a total length of
approximately one (1) kilometer. New and wider bridge decking (8 lanes) consisting
of pre-stressed U-Beams and R. C. Deck Slabs shall be utilized. It is envisaged that
the rehabilitation works would result to improved volume capacity, riding quality and
structural integrity.
During the pre-construction and construction period, a traffic management plan shall
be implemented. This would entail the widening of the at-grade service road,
provision f traffic barricades, signages, field personnel and the construction of
temporary detour roads.
2.3.1.2
Alabang to Calamba (TR-2)
The rehabilitation and expansion program for this section will consist mainly of the
following:
1. Rehabilitation and/or reconstruction of the existing pavement;
2. Construction of an additional two (2) lane carriageway (both directions) from
Alabang to Santa Rosa and a one (1) lane carriageway (both directions) from
Santa Rosa to Calamba;
3. Construction of an additional traffic lane for the whole length (both directions);
4. Upgrading and extension of the existing drainage system;
5. Widening of existing underbridges and overpasses where necessary to
accommodate the additional traffic lanes;
6. Seismic retro fitting of the underbridges and overpasses where necessary;
7. Repair and/or replacement of the existing boundary fencing; and
8. Improvement and/or replacement of ancillary structures.
2.3.1.3
Calamba, Laguna to Santo Tomas, Batangas (TR-3)
This section will require the construction of a dual two-lane carriageway on a new
alignment. This will also entail the construction f new bridges, farm crossings,
approach roads, retaining and slope protection structures and ancillary works. In
addition, a dual two-lane 1.5-kilometer spur road link to the Southern Tagalog Arterial
Road (STAR) will be constructed.
2.3.2
Summary of Major Structures
Table 2.1 shows the structural works that have to be undertaken at specific locations
identified during the preliminary investigation conducted.
TABLE 2. 1 SUMMARY OF STRUCTURAL WORKS
Rehabilitation And Replacement Of
Superstructure
Alabang Viaduct (TR-1)
Alabang-Calamba (TR-2)
Widening of underbridges
Seismic Retrofitting (subject to review of
existing structures)
Underbridges
Overpasses
Toll Plaza and Facilities
Calamba – Sto. Tomas
16 sites (2 bridges per site)
Overpasses
3 (1 farm crossing and 2 barangay crossings)
excluding Ayala Greenfields
5 sites (excluding the LISP)
Sto. Tomas Junction
Underpass Bridges
Toll Plaza and Facilities
16 sites (2 bridges per site)
24 locations
12 sites
2.3.3
Design Criteria and Standards
The basic design criteria will follow the existing alignment of the South Luzon
Expressway. Where land permits, local improvements will be undertaken. The
crossfall of the existing highway will be improved to 2.5% and a third inner lane shall
be added. As a result of the reduction of the median, a revised median treatment
shall be developed.
The outer shoulder width will be 2.5 meters while each traffic lane shall be 3.5 meters
wide. The proposed widening shall be undertaken towards the inner portion of the
roadway except that of the Alabang to Santa Rosa section which would be
undertaken (widening from 2 lanes to 4 lanes both directions) at the outer portion.
2.3.3.1
Geometric Standards
Toll Road 1
This section is an existing viaduct that will be rehabilitated and improved. The
viaduct will have new superstructures and the substructures will be retrofitted and/or
strengthened.
Toll Road 2
This section is an upgrading of the existing roadway with the alignment generally
following the existing alignment with localized improvements. Table 2.2 shows the
standards and technical specifications that will be utilized in this section.
TABLE 2. 2 STANDARDS AND TECHNICAL SPECIFICATIONS-TOLL ROAD 2
DESIGN ELEMENT
Terrain Condition
Design Speed (kph)
Number of Lanes
Lane Width (m)
Median Width (m)
Inner Shoulder (m)
Outer Shoulder (m)
Minimum Radius of Curvature (m)
Maximum Gradient (%)
Superelevation Rate (%)
Desirable
Maximum
Crossfall of Carriageway (%)*
Crossfall of Shoulder (%)
RECOMMENDED VALUES
Flat
Rolling
100
3
3.50
5.00
1.00
2.50
550.00
3.00
3.00
5.00
2.50
80
3
3.50
5.00
1.00
2.50
550.00
4.00
3.00
5.00
2.50
DESIGN ELEMENT
Terrain Condition
At Grade
At Structure
Vertical Clearance (m)
Above Roadway
Above Railway
RECOMMENDED VALUES
Flat
Rolling
4.00
2.50
4.00
2.50
5.08
6.80
5.08
6.80
*Crossfall to be increased to 2.5% where existing structures are not affected
Toll Road 3
This section would involve new works and new construction. Table 2.3 shows the
standards and technical specifications that will be utilized in this section.
TABLE 2. 3 STANDARDS AND TECHNICAL SPECIFICATIONS – TOLL ROAD 3
DESIGN ELEMENT
RECOMMENDED VALUES
Terrain Condition
Flat
Design Speed (kph)
Rolling
100
80
3
3
3.65
3.65
12.00
12.00
Two Traffic Lane
1.20
1.20
Outer Shoulder (m)
3.00
3.00
550.00
550.00
3.00
4.00
Desirable
3.00
3.00
Maximum
5.00
5.00
2.50
2.50
At Grade
4.00
4.00
At Structure
2.50
2.50
Above Roadway
5.08
5.08
Above Railway
6.80
6.80
Number of Lanes
Lane Width (m)
Median Width (m)
Dual Carriageway
Two Traffic Lane
Inner Shoulder (m)
Dual Carriageway
Minimum Radius of Curvature (m)
Maximum Gradient (%)
Vertical Clearance (m)
New Ramps
Table 2.4 presents the standards and technical specifications that will be utilized in
the construction of these structures.
TABLE 2. 4 STANDARDS AND TECHNICAL SPECIFICATIONS – NEW RAMPS
DESIGN ELEMENT
RECOMMENDED VALUES
Traffic Condition
A
B
C
Design Speed (kph)
Desirable
70
70
70
Minimum
40
40
40
Lane Width (m)
5.80
6.40
7.00
Shoulder Width [m] (Inner and Outer)
1.10
1.10
1.10
Desirable
160.00
160.00
160.00
Minimum
50.00
50.00
50.00
Desirable
2.00
2.00
2.00
Maximum
6.00
6.00
6.00
2.50
2.50
2.50
2.50
2.50
2.50
4.00
4.00
4.00
Minimum Lateral Clearance from Edge
of Paved Shoulder (m)
2.00
2.00
2.00
Minimum Radius of Curvature on Inner
Edge of Pavement (m)
Gradient (%)
Existing Ramps
These Ramps will be rehabilitated to existing geometric specification and Standards.
2.3.3.2
Engineering Design Standards
Table 2.5 presents the Standards to be adopted for the various areas of engineering
design of the project.
TABLE 2. 5 ENGINEERING DESIGN STANDARDS
DESCRIPTION
Pavement Design
STANDARD
•
•
Hydrology and Drainage
•
•
•
Bridges
•
•
•
•
•
•
•
•
Lighting
•
•
•
•
•
•
DPWH Standard Specifications for Public Works and
Highways, Volume 2
American Association of State Highway and
Transportation Officials (AASHTO) – Guide for
Design of Pavement Structures (1993 Edition)
Soil Conservation Service Guidelines
Department of Public Works and Highways (DPWH)
Design Guidelines, Criteria and Standards (1998)
AASHTO Highway Drainage Guidelines
DPWH Standard Specifications for Public Works and
Highways, Vols. 2 & 3, 1995 Edition
Standard Specification for Highway Bridges, AASHTO
16th Edition, 1996 (which includes Division I-A
Seismic Design)
National Structural Code of the Philippines (NSCP)
Vol. 1 4th Edition, 1992
NSCP Vol. II for Bridges 2nd Edition, 1997
American Concrete Institute (ACI) Code 318-95
DPWH Retrofitting Guidelines for Highway Bridges in
the Philippines, 1993
DPWH Department Order No. 75 Series of 1992 re:
Advisory Seismic Design of Highway Bridges
Seismic Retrofitting Manual fro Highway
Administration, US Department of Transportation
Philippine Electrical Code Part 2, Appendix G-Street
Lighting Guide, 1988
Illuminating Engineers Society Lighting Handbook,
Application Volume, Section 14 – Roadway Lighting,
1981
British Standard BS 5489, Road Lighting, Parts 1, 5,
6, 8, and 10
Commission Internationale de l’ Eclairage
Publication No. 23 (TC-1.6), International
Recommendations for Motorway Lighting (1972)
Publication No. 30.2 (TC-4.6), Calculation and
Measurement of Illuminance in Road Lighting (1982)
2nd Edition
for the South Luzon Tollways Extension Project
TABLE OF CONTENTS - 1
TABLE OF CONTENTS
3
DESCRIPTION OF ENVIRONMENTAL SETTING AND RECEIVING ENVIRONMENT 1
3.1
PHYSICAL ENVIRONMENT .......................................................................................... 1
3.1.1 Land and Resource Use...................................................................................... 1
3.1.2 Regional Geology................................................................................................ 6
3.1.3 Local Geology ..................................................................................................... 6
3.1.3.1 Quaternary Alluvium ..................................................................................... 6
3.1.3.2 Pleistocene Laguna Tuff............................................................................... 6
3.1.3.3 Volcanic Cinder Deposits ............................................................................. 8
3.1.3.4 Volcanic Flow/Agglomerate .......................................................................... 8
3.1.4 Geologic Structures............................................................................................. 9
3.1.4.1 Faults............................................................................................................ 9
3.1.4.2 Folds............................................................................................................. 9
3.1.4.3 Vulcanism ..................................................................................................... 9
3.1.5 Geologic Hazard................................................................................................ 11
3.1.6 Volcanic Eruptions and Associated Hazards..................................................... 11
3.1.7 Tectonic and Seismicity..................................................................................... 13
3.1.8 Philippine Fault (PF).......................................................................................... 13
3.1.9 Lubang Fault (LF).............................................................................................. 16
3.1.10
West Marikina Valley Fault System (MVFS).................................................. 16
3.1.11
Athmospheric Environment ........................................................................... 18
3.1.11.1 General Climate.......................................................................................... 18
3.1.11.2 Wind ........................................................................................................... 18
3.1.11.3 Precipitation................................................................................................ 18
3.1.11.4 Temperature ............................................................................................... 18
3.1.11.5 Relative Humidity........................................................................................ 35
3.1.11.6 Tropical Cyclones ....................................................................................... 35
3.1.12
Air Quality and Ambient Noise Measurements.............................................. 35
3.2
BIOLOGICAL ENVIRONMENT ..................................................................................... 43
3.2.1 Terrestrial Ecology ............................................................................................ 43
3.2.1.1 Flora ........................................................................................................... 44
3.2.1.2 Vegetation Analysis .................................................................................... 46
3.2.1.3 Wildlife and Other Fauna............................................................................ 48
LIST OF TABLES
TABLE 3. 1 CLIMATOLOGICAL NORMALS FOR AMBULONG STATION, BATANGAS AS OF 2000......................... 20
TABLE 3. 2 CLIMATOLOGICAL EXTREMES FOR AMBULONG STATION, BATANGAS AS OF 2003 ....................... 21
TABLE 3. 3 SOURCES OF AIR POLLUTION IN THE STUDY AREA ................................................................... 35
TABLE 3. 4 AIR POLLUTION INDICATORS AND LEVEL OF SIGNIFICANCE IN THE STUDY AREA ........................ 37
TABLE 3. 5 NATIONAL AMBIENT AIR QUALITY STANDARDS FROM MOBILE AND STATIONARY SOURCES ......... 37
TABLE 3. 6 ON-SITE MEASUREMENTS FOR TOTAL SUSPENDED PARTICULATE MATTERS (TSP) .................. 38
TABLE 3. 7 RESULTS FOR THE SAMPLING FOR SULFUR DIOXIDE (SO2) AND NITROGEN DIOXIDE (NO2) ...... 39
TABLE 3. 8 AMBIENT NOISE MEASUREMENTS ............................................................................................ 41
TABLE 3. 9 TYPICAL NOISE LEVELS PRODUCED BY CONSTRUCTION EQUIPMENT......................................... 42
TABLE 3. 10 NOISE LEVELS AT VARIOUS DISTANCES FROM THE SOURCE .................................................. 43
TABLE 3. 11 LIST OF FLORAL SPECIES SURVEYED .................................................................................... 45
TABLE 3. 12 SUMMARY OF DATA FROM LINE INTERCEPT SAMPLING .......................................................... 47
TABLE 3. 13 FAUNAL COMPONENTS ......................................................................................................... 48
for the South Luzon Tollways Extension Project
TABLE OF CONTENTS - 2
LIST OF FIGURES
FIGURE 3. 1 LAND USE MAP OF CALAMBA CITY .......................................................................................... 2
FIGURE 3. 2 MAP OF FOREST CONSERVATION AREAS IN THE STUDY AREA .................................................. 4
FIGURE 3. 3 LAND USE MAP OF STO. TOMAS, BATANGAS ............................................................................ 5
FIGURE 3. 4 GEOLOGIC MAP OF THE PROJECT SITE .................................................................................... 7
FIGURE 3. 5 MAP OF THE REGIONAL STRUCTURAL FEATURES ................................................................... 10
FIGURE 3. 6 MAP OF ACTIVE AND INACTIVE VOLCANOES IN THE PHILIPPINES ............................................ 14
FIGURE 3. 7 MAP OF THE SIGNIFICANT EARTHQUAKE GENERATORS IN PROXIMITY TO THE STUDY AREA ...... 15
FIGURE 3. 8 MAP SHOWING SUMMARY OF IMPACTS OF JULY 16, 1990 LUZON EARTHQUAKE ...................... 17
FIGURE 3. 9 MODIFIED CORONAS SYSTEM OF CLIMATE CLASSIFICATION .................................................... 19
FIGURE 3. 10 MONTHLY WIND ROSE – JANUARY....................................................................................... 22
FIGURE 3. 11 MONTHLY WIND ROSE – FEBRUARY .................................................................................... 23
FIGURE 3. 12 MONTHLY WIND ROSE – MARCH ......................................................................................... 24
FIGURE 3. 13 MONTHLY WIND ROSE – APRIL............................................................................................ 25
FIGURE 3. 14 MONTHLY WIND ROSE – MAY.............................................................................................. 26
FIGURE 3. 15 MONTHLY WIND ROSE – JUNE ............................................................................................ 27
FIGURE 3. 16 MONTHLY WIND ROSE – JULY ............................................................................................. 28
FIGURE 3. 17 MONTHLY WIND ROSE – AUGUST ........................................................................................ 29
FIGURE 3. 18 MONTHLY WIND ROSE – SEPTEMBER .................................................................................. 30
FIGURE 3. 19 MONTHLY WIND ROSE – OCTOBER...................................................................................... 31
FIGURE 3. 20 MONTHLY WIND ROSE – NOVEMBER ................................................................................... 32
FIGURE 3. 21 MONTHLY WIND ROSE – DECEMBER ................................................................................... 33
FIGURE 3. 22 ANNUAL WIND ROSE........................................................................................................... 34
FIGURE 3. 23 FREQUENCY OF TROPICAL CYCLONE PASSAGE IN THE PHILIPPINES ...................................... 36
DESCRIPTION OF ENVIRONMENTAL SETTING AND RECEIVING ENVIRONMENT - 1
3
DESCRIPTION
OF
ENVIRONMENTAL
RECEIVING ENVIRONMENT
3.1
PHYSICAL ENVIRONMENT
3.1.1
SETTING
AND
Land and Resource Use
Calamba, Laguna is a progressive municipality occupying a total land area of 14,480
hectares. It is comprised of fifty-four (54) barangays, twenty-five (25) of which are
classified as urban covering an area of 3,351 hectares or 23% of the municipality’s
total land area. The rest are classified as rural encompassing twenty-nine (29)
barangays with an aggregate area of 11,129 hectares or covering 77% of the total
land area.
Calamba, is among the four (4) municipalities that have been cited as an urban
corridor in Region IV. The strategy is to develop the area into interrelated urban,
industrial, commercial and educational/cultural center comparable to Metropolitan
Manila. The major land uses of Calamba are as follows: industrial; residential;
agricultural; agro-industrial; forest conservation; tourist recreation; commercial and
institutional (see Figure 3.1 for Land Use Map of Calamba City).
Manufacturing companies are located in various barangays zoned as industrial area.
Industrial activities are highly concentrated at Barangay Canlubang in terms of the
number of existing firms, although Barangays Mayapa, Paciano Rizal, San Cristobal,
Real, Makiling, Tulo and Turbina have also their share in the industrial growth.
Heavy manufacturing industries are mostly located in Barangays Makiling, Tulo and
Turbina, while light and medium industries are found in Barangays Canlubang, Real
and Sirang Lupa. Medium manufacturing industries are also usually established in
Barangay San Cristobal. The nature of manufacturing industries includes food
production, garments/textile, plastic manufacturing, agricultural, pharmaceutical /
chemical production, metal, paper, electrical, auto parts, and others. Quarrying
activities are also present at Barangay Puting Lupa.
There are 51 registered residential subdivisions located in twenty-three (23)
barangays. Mostly middle and high-income families inhabit these subdivisions.
Clusters of human settlements can also be found along the shorelines of Laguna de
Bay and interspersed with commercial and business establishments along the
national highway and other major roads of the town proper.
Total arable area is estimated at 8,292 hectares comprising about 57% of the
municipality’s total land area. Total land area cultivated is estimated at only about
5,182 hectares. Crops predominantly cultivated include rice, sugar cane, and
vegetables. In upland barangays of the western side of Calamba, farmers also
engage in livestock and poultry production.
Calamba is also endowed with natural and man-made attractions for tourism. The
natural attractions include hot and cold springs in Barangay Bucal and Pansol, the
Crocodile Lake in Barangay Masile and the Wonder Island in Barangay Lingga.
Man-made attractions include the Shrine of Dr. Jose P. Rizal and the “Banga” at the
town plaza and seventy-seven (77) registered resorts and privately owned swimming
pools mostly found in Barangay Pansol. Forest conservation areas are located within
the Mt. Makiling Forest Reserve and its vicinity as shown in Figure 3.2.
Commercial areas included the Poblacion, the Crossing area at Barangays 1 and
Parian. The Poblacion is the center of commercial activities in Calamba. The public
market, located at the central Poblacion is considered the most complete commercial
building in the municipality, covering an area of 25,835 sqm.
Commercial
establishments are engaged in retail, wholesale, services, banking and finance,
insurance and real estate activities.
The municipality of Sto. Tomas is one of the 32 municipalities of Batangas Province.
It is located at the northeastern section of the province. It is bounded at the west by
the San Juan Riverm at the north by Sian-Sian River and ridges of Mt. Makiling, at
the northeast by the Alas-as River, and at the southeast by San Juan River.
Municipality-wise, by Calamba in the north; Bay and Alaminos in the east, Tanauan
and Malvar in the west; and Lipa City in the South.
The northeastern part of Sto. Tomas is somewhat mountainous being a portion of
Mount Makiling. The rest of the municipality is generally plain with an elevation of
about 38 to 37 masl. The town proper where the seat of government lies has an
elevation of 42 masl.
Sto. Tomas, Batangas is a highly industrialized area being a major location for light to
heavy industrial facilities. It has a total land area of 9,540 hectares. It is comprised
of 30 barangays. See Figure 3.3 for the land use map of Sto. Tomas, Municipality.
3.1.2
Regional Geology
The collision of the plates created the volcanic arc that links the Taal Volcano to Mt.
Mariveles, Mt. Natib and Mt. Pinatubo to form the western volcanic zone known as
the Macolod Corridor.
The oldest rock in the region is the volcanic flow of andesite and basalt, intruded by
cinder cones along east-west and north-south directions, and finally deposition of the
volcanic tuff over the older rocks. Mountain ranges consist of the volcanic flows and
cinder cones.
3.1.3
Local Geology
The Project site is underlain by Quaternary Alluvium, Pleistocene Laguna Tuff
Formation, Volcanic Cinder and Andesite Flow successively from youngest to the
oldest deposit. See Figure 3.4 for the Geologic Map of the Project Site.
3.1.3.1
Quaternary Alluvium
This consists of products of weathering of older existing rocks, eroded and deposited
in alluvial plains and fans, in dissected rivers and creeks, and in coastal areas of
Laguna de Bay and transported as residual soil.
3.1.3.2
Pleistocene Laguna Tuff
Unconformably this overlies the older volcanic cinder deposits and volcanic
flow/agglomerate. It is the most widely distributed deposit and generally occurs as
the cover rock for topographic lows and as thin blanket covering the tops of ridges
composed of volcanic cinders and andesite flows and agglomerates.
Two sections of tuff deposits were noted, namely: the Upper Section is a younger tuff
which is described as thickly bedded, interbedded fine-grained tuff and lapili tuff;
poorly cemented and unconsolidated, that underlies topographic lows; and the Lower
Section is an older tuff, described as thinly bedded well cemented and consolidated,
that underlies areas with higher relief. Strike and dip measurements indicate
northeast and northwest trends with low to almost horizon dips.
3.1.3.3
Volcanic Cinder Deposits
Cinder cones overlay the older volcanic flows, both of which are overlain by the
Laguna Tuff. It comprises the conical shape mountain peaks. Three parasitic cinder
cones are located within or adjacent to the Project site, which have been previously
quarried. There are: Mt. Malaraya (Mt. Masaia) in the Putting Lupa area, which is a
cinder cone which was formerly quarried by a certain Mr. Morales located near the
Science Park area; and the cinder cone in Mt. Camotes in Barangay Kamaligan just
outside of the Project area.
Black and red cinder deposits were observed. At the southern foothill of the volcanic
cone of Mt. Malaraya (Mt. Masaia), a 5 to 6 meters thick black cinder was observed
to overlie the thicker reddish (hematitic) cinder basement.
3.1.3.4
Volcanic Flow/Agglomerate
Considered as the oldest and the basement rock, it is a volcanic flow that is closely
associated with agglomerate. It occurs extensively in the eastern side of the Project
site where it is currently being exploited as concrete aggregate in Mt. Ambrosio (Mt.
Maibararo) and at Barangay Maunong.
The volcanic flow appearing in quarries is chiefly andesite, which is generally porous,
vesicular and highly jointed; which makes it a poor quality aggregate. However the
andesite occurrence in Puting Lupa, (Purok 3, about 350 meters from the road
intersection with the road going to Kamaligan) is fine-grained, porphyritic, more
dense CK with draft and harder than those appearing in existing quarries.
At the foothill of Mt. Tagaytay (Mt. Bijiang), the andesite has highly hydrothermally
altered into kaolinite.
Agglomerate occurs at the base of the old quarry site of Mt. Morales. The
agglomerate is composed of angular or subangular class of andesite and tuff
fragments (about 10-20 cm in diameter) embedded in a grayish sandy tuff matrix. It
is well cemented and comparatively harder than the other rock occurrences.
3.1.4
Geologic Structures
3.1.4.1
Faults
Figure 3.5 shows the regional structural features. Four (4) sets of northeastsoutheast trending parallel faults are recognized near the project site. These faults
(labeled as I, II, III and IV) relative to the Project site are located 3, 6, 9 and 11 kms
southeast of the project. Hot springs occurring in the Calamba and the Los Baños
areas are attributed to these faults. These Faults have high dips and are presumably
gravity faults, which are genetically related to the volcanic activity in the area.
Parallel to the National Road from Calamba through Tanauan, Batangas is a semicircular volcano tectonic fault occurring west of the Project site. It appears to have a
concentric trend relative to Mt. Makiling, thus suggestive of an origin related to the
volcano for Mt. Makiling. No active faults were mapped within the Project site.
Extensive mapping showed nearly horizontal inclination of the pyroclastic formation
and scarsity of joints in the rocks; indicating that there had been no significant
tectonic disturbance.
3.1.4.2
Folds
The abrupt changes in strikes and dips in Mt. Camotes suggest the nose of an
anticline or a depositional gap between the flat dipping underlying volcanic cinder
deposits. The sharp contrast in the degree of inclination of the tuff and the volcanic
cinder deposit is interpreted by some geologists, as being due to past tectonism
which was operational during and shortly after the deposition of the older cinder
deposits. Tectonic movements had only affected the cinder deposit and had ceased
to operate during and after the deposition of the tuff.
3.1.4.3
Vulcanism
Two prominent volcanic peaks namely Mt. Makiling and Mt. Bulalo are located 7 km
southeast and 12 km southeast of the Project site, respectively. Mt. Makiling is a
stratovolcano with a summit caldera which towers 1115 masl, whereas Mt. Bulalo is a
lava dome extruded in its base. The volcanic cinder cones inside the Project site are
parts of volcanic features of Mt. Makiling. Based on studies of PHILVOCS, there is
no historical record of Mt. Makiling and Mt. Bulalo past eruptive activities. The
presence of welded tuff around Mt. Makiling strongly suggests that previous
eruptions hundreds of thousand years ago had been violent.
Present volcanic activity of Mt. Makiling is limited to hot springs, solfatara, some
streaming vents and mud springs. These are very evident on the northern part of Mt.
Makiling in the Calamba area.
3.1.5
Geologic Hazard
Earthquakes and Associated Hazards
Ground Shaking
With risks of collapse and overturn of buildings or
infrastructures causing loss of lives and injuries to
people and damage to properties.
Ground Rupture
With risks of differential subsidence, collapse of
infrastructures causing loss of lives and injuries to
people and damage to properties.
Landslide and Mass Movement
With risks of damage to infrastructures and cutoff of communication/transport route.
Liquifaction
With risks of differential settlement and tilting of
structures and floods in farmlands.
Tsunami
With risks of loss of lives and injuries to people, and
flooding in coastal areas.
3.1.6
Volcanic Eruptions and Associated Hazards
Ashfall, Tephra
Risks are mainly on damage to structures.
Base Surge, Ballistic
Lahar and Mudflow
Gases and Other Emissions Risks in the impact on health of people.
Earthquakes with magnitudes equal or greater than 6.0 normally cause severe
shaking that can cause damage to inadequately designed structures that will not be
able to resist the maximum ground acceleration resulting from the earthquake. Also
due to the weak nature of the physical parameters of the foundation material, the
bearing capacity is exceeded, and by the use of weak construction materials
shearing may occur leading to the collapse of infrastructures.
Marikina Valley Fault System (MVFS) is considered the most significant earthquake
course relative to the Project due to its being the nearest earthquake source, hence
the PGA for it was computed, which for M=6.8, and the minimum distance of 25 km
from the Project site turned out to be PGA=0.4g. This is the design acceleration
factor that should be adopted. However, due to the physical parameter of the
foundation material, the corresponding G-factor for rocks is from 0.22 to 0.24g and
for medium soil from 0.4 to 0.45g based on a 10% probability that M=6.5 will be
exceeded during a project life of 25 years. Other ground parameters are:
velocity=24.19 cm/sec and 7.8 cm displacement.
Mainly because of the geologically young age of the rocks, the soil mantle is
generally limited to 1 to 2 m in thickness. With residual soil of limited thickness, the
structures will be founded on tuff or volcanic cinder or andesite/agglomerate after the
removal of the thin soil cover.
Hence, the mitigation measure is to use the design acceleration factor of 0.4g and
select construction materials that can resist the stresses.
Ground rupture occurs along a fault trace where the earthquake event occurs.
Hence, the mitigation measure is to avoid the construction of the structure on top of
the active fault or offset the construction at least 5 m away. However, since there are
no recognized or identified active faults within the Project site, there is no mitigating
measure recommended.
Landslide or mass movement can be triggered off by a strong earthquake on loose
materials piled on unstable slopes especially when the loose materials are saturated
with water during heavy rains. The mitigating measures are to maintain slope
stability by engineering measures such as rip-rap, etc., reduction of cut-slopes; by
terracing; prevent increase of internal water content by vegetation cover, etc.; by
adequate drainage control; and setting up of warning devices, to warn the public of
the event. To mitigate the negative impact, an engineering geologist should assess
the current state of the slopes of loose materials in order to pin-point potential
landslide prone areas and to apply the appropriate control and remedial measures.
The stability of slopes within the property was studied, particularly portions with high
relief, but no large-scale natural landslide was noted. Only a minor scale failure
caused by quarrying operations was noted at the southeast side of Mt. Malaraya in
Putting Lupa, which should be addressed.
Liquifaction will occur where well sorted sands with no or minimal amount of clay and
shallow water table occurs.
Since the bedrock in the Project site occurs at shallow depths, liquefaction is least
likely to occur, but borehole and grain size studies should still be conducted. Hence,
the mitigation measure is to conduct borehole and grain size studies complete with
geo-resistivity survey to complete the final plans and foundation designs. Tsunami
occurs when the earthquake event occurs in a large body of water, which results, to
the production of large waves that may impact the shoreline causing damage to
properties and loss of lives in coastal areas. However, as the Project is several
kilometers upland from the Laguna de Bay, this hazard will have no negative impact
at all.
A map of active and inactive volcanoes in the Philippines is known in Figure 3.6.
Both Mt. Makiling and Mt. Bulalo are currently inactive. The only nearby active
volcanoes are the Taal Volano and Mt. Banahaw which are both 60 km away from
the Project site. Hence the most serious impact should either one or both erupt is to
spew out columns of volcanic ashes/tephra, base surge, lahar (mudflow) gases and
other emissions.
3.1.7
Tectonic and Seismicity
The collision of the Philippine Sea Plate and the Eurasian Plate brought about the
Philippine Archipelago by island arcs, mountain building, volcanic arcs, trenches,
subsequent depositional basins, submergence and rise of coastal areas deformation
such as folds and faults, any or combination of which gave rise to zones of
earthquake generators. Regional seismicity in the Project site is influenced by any of
the earthquake generators situated two or three hundred kilometers from the Project
site, with intensities varying inversely with the distance.
The following are the notable earthquake generators: Philippine Fault (PF); Verde
Island Passage Transform Fault or the Lubang Fault (LF); and Marikina Valley Fault
System (MVFS), consisting of western and eastern component. The more significant
earthquake generators that may affect the project are the Philippine Fault, the
Lubang Fault and the West Marikina Valley Fault (See Figure 3.7).
3.1.8
Philippine Fault (PF)
The PF is a major active strike slip fault with a rupture length of 1200 km extending
from eastern Mindanao, through the Visayas Islands, and through eastern and
northern Luzon. Within historic times, at least three large earthquakes with
magnitude Ms greater than 7.0 are attributed to movement along PF.
The most recent of which is the July 16, 1990 event with epicenter in Nueva Ecija
(See Figure 3.8) and Ms 7.8; the Ms=7.3 Ragay Gulf earthquake on March 17, 1973;
and the August 20, 1973 Ms of 7.3 event which ruptured along the offshore area of
Lamon Bay. The projections of the PF closest to the project site is about 75 km.
3.1.9
Lubang Fault (LF)
LF is a northwest-southeast trending active fault occurring in between Mindoro Island
and Batangas Province and is correlated with Plestocene volcanism. LF has a
rupture length of approximately 190 km and lies about 90 km south of the Project
area. The following earthquake events such as the 1942 event with a Ms of 7.6 and
the 1994 event with Ms of 7.1 can be attributed to this fault.
3.1.10
West Marikina Valley Fault System (MVFS)
West MVFS is a north-northeast trending 80 km long fault structure that extends from
Angat, Bulacan southward to the north of Taal Lake where it is cut by an east-west
trending fault structure.
West MVFS traverses the coastal area west of Laguna de Bay and dips steeply to
the east as a nomal slip fault.
Field survey conducted by a PHILVOCS team claimed to have gathered
morphotectonic evidence of dextral (right lateral) strike slip movement in 1990-1991.
Evidence included displaced scarps, offset streams and alluvial fans, shutter and
pressure ridges. However, there are no known earthquake events nor displaced
Holocene alluvial deposits that are attributed within historical times.
As no earthquake event can be attributed to the MVFS, a probable magnitude was
calculate based on the Wells and Coppersmith 1977 equation M=5.08 + 1.16 log
(SRL) whereby SRL is the effective Surface Rupture Length assumed to be 20 km.
Probable magnitude ranges from 6.5 to 7.0 with recurrence period of 300 to 400
years.
Recurrently, low fault slip movement known as fault creeps were observes along a
segment of the west MVFS in the Muntinlupa-San Pedro-Biñan area. This ground
rupture has affected residential and industrial buildings but has not generated large
damaging earthquakes. The trace of the west MVFS closest to the project site is
about 25 km.
3.1.11
Athmospheric Environment
3.1.11.1
General Climate
As shown in Figure 3.9 the Modified Coronas’ Scheme of Climate Classification the
climate of the proposed site may also be categorized as wet and dry season. The
wet season occurs from June to November and the dry season occurring from
December to May.
The average annual rainfall is 1950.80 mm. The mean annual temperature is 27.60
ºC, the number of rainfall days is 130, relative humidity is 78%, and the average
annual wind speed is 2.0 m/s with highest value registering 80 m/s. Table 3.1 and
Table 3.2 show Climatic Normals and Extremes of Ambulong Station, Batangas as of
2000 and 2003.
3.1.11.2
Wind
Monthly wind rose provides a general picture on wind speed and direction.
Prevailing winds varies from 1 to 2 m/s directed northeast. The mountain terrain
shielded the area from the effects of the southwest monsoon. Generally, the
northeast monsoon affects the area in the months of November to April. Figures
3.10 to 3.22 show the monthly and annual wind roses.
3.1.11.3
Precipitation
Meteorological data from PAGASA, Ambulong Station, Batangas reveals that the
annual average rainfall is 1950.80 mm. Generally, higher precipitation occurs from
May to December recorded at 10-18 days during the southwest monsoon. There is a
relatively dry period from January to April with only 9.9 mm rainfall in February
occurring in only 2 days. Highest monthly rainfall is 358.7 mm in July occurring in 18
days.
3.1.11.4
Temperature
The average annual temperature is 27.60ºC. The month of May registered the
highest temperature at 29.0ºC while February registered the lowest at 21.7ºC. On
the other hand, climatological extremes have recorded temperature levels as high as
38.80ºC on 15 May 1921 and lowest of 13.40ºC on 26 November 1901. Because of
the rural nature of of the study area, the temperature may be lower than estimated.

table of contents

Transcription

Similar documents

District Deputy District Deputy

spc disaster risk reduction management core team meeting

LPU Batangas vicinity map - Lyceum of the Philippines University

Wildlife Times

7. volcanic eruptions - e-GEOS

Batangas State University

Vol 4 No 14.pmd

Indang - Nerbac Calabarzon

Gov welcomes Drilon, Alunan at Capitol

Volcanic hazard in East Africa